Don't take this the wrong way, it's great you're doing this and you seem to have good mechanical and electrical skills but... you're doing things in the wrong order and making it way too hard.

If you had done the power balance test first you would know not to bother with all the other things you've tested. And tearing it down again and again might make more issues.

If you really want to figure it out you need a scanner with that reads the OEM datastream to read each cylinders misfire counters, these are as cheap as $100 these days. The scanner will also have the freeze frame for when the P0300 code is being set, this is a snapshot of the datastream before and after the code trigger. Looking through that you can find clues to the root cause of the problem.

I checked through IATN.net's repair archives. Over 20 similar cases w/ vq35de, head gaskets, AF sensors, leaking plenum gaskets, valvetrain issue, no common problem that jumps out.

If you need any ALLDATA wiring diagrams or stuff I can get that at work.

 

Any resolution OP? I too have P0300, but my symptoms are very different.

 

Not fixed yet. I'm taking it to Nissan (Infiniti) or a good shop. But I'm moving and it'll have to wait.

 

FYI, turned out to be catalytic converters.

 

Probably due to plugs 4/6 reversed... dumping fuel into cats for more than a couple miles will melt them real quick.

 

Thanks for the update OP.

 

Oh man I should have thought of that. When my car started the same code the first thing I checked was my cats. I guess bc that turned out not to be the problem I didn't think to mention it. Glad you got it sorted out!

 

I'm having the same issue with p0300 and some other codes. Started happening about 2 weeks after turbo install. I have no cats. But I do have new injectors, spark plugs and fuel pump. Sometimes it has trouble starting and I have to pump the gas. And sometime the engine will just stall while I'm driving. The cel clears itself sometimes and will end up coming back.

 

i took out all 6 injectors in search of the "black" one which would indicate a faulty leaky injector.. they all look very similar to me.. and the tips all look white. can anyone confirm this? or is anyone able to see the faulty one?

 

They all look similar but the top image the 2 plugs on the right look darker than all the rest. Of course they won't be black because the car will run mostly around stoich but they seem just a little more tan.

I can't see the ground strap very well on them. The center electrode looks kind of rounded off and worn on most of them which indicates some wear. Without seeing them in person or an upclose high res picture it would be hard to find problems. Also since the misfire happens on occasion and not every single engine cycle they will burn off some of that excess fuel if it there is fuel build up.

 

Would you mind pointing out a code reader that does what you are talking about? I already have a medium priced Innova that does live data and datalogging but never have seen misfire counters. This one is at least 5 years old. Maybe I need to update the firmware or maybe I need a more modern scanner Can you give me a hint so I can help myself? I am reading all of these threads on misfires and not getting very far like most people! Need to take advice that saves the time I don't have right now!

 

I am just not having luck with this one part. My head must be really thick on this one! I have performed a few of the 19 tests in the FSM but want to attack it instead with either a power balance test or misfire counter analysis because I can see how helpful that would be and save so much time and guessing. I now have another mid priced scanner that probably needs to be returned. I had a Innova 3130 that has been OK until this P0300 came up and I bought a Centech 60694/Autel Al519 today because it says that is supports all 10 Modes of OBDII data but it just seems like the same data from the 3130 displayed in a different way. I still have no access to raw or stored misfire counters per cylinder that I can find! I realize that this route would be much easier than working my way through all of the 19 or so tests in the FSM but I'm struggling to find the correct tool. I am open to software too instead of a handheld. Whatever is cheaper/best bang for my buck. Probably under $300
Don't all OBD systems have to have the misfire counters in there? I'm just buying the wrong scanner right?

 

Someone from Autel got back to me and said things like this are vehicle specific. That explains why it is so difficult to pick out a scanner with the features you want because some of them depend on the vehicle...

If I pay Nissan to do a power balance test will it only reveal something if it is misfiring (whether I can feel it or not)? Or is that test sensitive enough to detect power imbalance at the level that you could not feel on your own and be worth the money?

 

Hi ...Hope you got your problem sorted...Would you mind telling me wot you did to get them sorted, coz I'm xperiencing the same...Thanx.... ps...This is for BLAKMAX

 

Hey dude..can you please tell me wot you did to sort out your issues, as I think my ride has the same...thanx

 

So I'm having the same code, i have greddy true duel exhaust, I have an 04 track, I can literally here the misfire only happening on the driver side which makes things a little bit easier for me. I'm in NY and I have heard that there are issues with the knock sensor for most nissan's in the cold, most times with the ignition coil you should get more than one code and the rpms should dance a little bit, not always but sometimes. I'm going to change my driver side knock sensor, I'll keep you all updated and let you know how it goes, fingers crossed.

 

And just as a side note on top of the p0300 code my car is bogging pretty bad under normal driving conditions, but at WOT the car feels fine, as well as when i start the car after it is at operating temp the rpm's drop and the car almost stalls, it idles fine though, just a little low between 400 to 600. if anyone possibly has any other possibilities on what else might cause this it would be appreciated.

 

My issue turned out to be a bad cat. The honeycomb separated from the interior of the cat and lodged itself sideways further down. New Berk HFCs solved my issues.

 

 

Infiniti replaced my CAT under warrantee. I don't recall the exact issue anymore.